Method and apparatus for forming fibers



Sept. 9, 1952 G. SLAYTER El AL METHOD AND APPARATUS FOR FORMING FIBERSFiled Dec. 31, 1948 4 Sheets-Sheet l INVENTOR. Qamea Sla- I'e'r' yCharleaJ glnle a Sept. 9, 1952 a. SLAYTER ETAL METHOD AND APPARATUS FORFORMING FIBERS 4 Sheets-Sheet 2 Filed Dec. 31, 1948 leg INVENTOR. .1\slayz'er A TOR/W015 3 U n i 4 7////////////// //////v- T7 ////J 6 I 4 Iif V/ Alli? 4 u M a 4 A Game BY Ckarle a p 9, 1952 s. SLAYTER ETAL2,609,566

METHOD AND APPARATUS FOR FORMING FIBERS Filed Dec. 551, 1948 4Sheets-Sheet 3 amea 61' By Char-Zea J 6,ZZe Z ATTORA/ZYJ' 4 Sheets-Sheet4 a .w J W? m 4 6d 7 O 1 VA 1 4 r ma a 6 ms 0 G. SLAYTER ET AL METHODAND APPARATUS FOR FORMING FIBERS Sept. 9, 1952 Filed Dec. a1. 1948 IOOIIIIIIII IA for efilcient operation.

Patented Sept. 9, 1952 METHOD AND APPARATUS FOR FORMING FIBERS GamesSlayter and Charles J. Stalego, Newark, Ohio, assignors to Owens-CorningFiberglas Corporation, Toledo, Ohio, a corporation of DelawareApplication December 31, 1948, Serial No. 68,664

12 Claims. 1

This invention relates to the manufacture of fibers from a materialwhich will soften in the presence of heat and which may be attenuated ordrawn out into fine fibers when in a softened state.

More particularly the invention refers to a process and apparatus formanufacturing on a commercial basis and at a high rate glass fibers ofone to five microns in diameter.

One satisfactory process for making fibers from glass or materialshaving similar characteristics is to melt a body of the material in afeeder having a multiplicity of small orifices in the bottom wallthrough which the molten material flows into the atmosphere in the formof streams. As the streams are introduced to the atmosphere theysolidify and are attenuated to produce individual primary filaments byfeed rolls which also serve to project the filaments into a blast of hotgas. The temperature of the blast exceeds the softening point of thematerial and the speed of the blast is sufficient to attenuate or drawout th softened material into fibers of the desired size.

While glass fibers of varying degrees of fineness ranging from onemicron or less in diameter to two and one-half microns or more indiameter have been successfully produced commercially by the processbriefly noted above, nevertheless, this general process has certaindisadvantages. One objection is that the process is ordinarily initiallystarted by manually pulling the individual streams and threading theprimary filaments into a grooved guide which usually occupies a positiondirectly below the feed rolls. This operation must be repeated followingeach intentional or accidental interruption of the process, and not onlyrequires skill on the part of the attendant, but also increases the downtime of the production equipment.

Also in order to facilitate handling of the streams or primaryfilaments, it has been the practice to provide a generous clearancebetween adjacent streams issuing from the feeder, and this clearance isordinarily greater than required In other words, the lateral spacingbetween adjacent primary filaments is ordinarily greater than would berequired if it were not necessary to handle the filaments duringstarting and accordingly full advantage of the capacity of the equipmentis not realized.

One of the objects of this invention is to provide an improved fiberforming apparatus of a design which is less likely to cause accidentalinterruption in the fiber forming hase, and is capable of substantiallycontinuous operation. Thus production losses due to equipment "down timeare materially reduced with a corresponding reduction in manufacturingcosts.

Another object of this invention is to provide fiber forming apparatusin which the actual operation of forming fibers need not be startedmanually after an interruption, but one in which attenuation of thematerial to fibers is resumed automatically without appreciable delayfollowing an interruption from any cause whatsoever. Inasmuch as it isnot necessary to handle the filaments the distance between adjacentfilaments may be reduced, and a greater number of filaments may be fedinto a fiber forming zone or blast of given width. As a result, thequantity of fibers produced with apparatus of a given size is increased,and the cost of manufacture is further reduced.

Still another object of this invention is to initially draw out a bodyof heat softened material such as glass into a multiplicity of primaryfilaments by the action of centrifugal force, and to finally attenuatethe filaments to form fine fibers by introducing the filaments endwiseinto a blast of gas having a temperature which exceeds the softeningtemperature of the material and having a velocity sufilciently high toprovide the force required to reduce the filaments to fibers of thedesired size. In accordance with this invention the magnitude of thecentrifugal force is not only sufficient to initially draw out the heatsoftened glass and form filaments, but is also sufficient to project thefilaments endwise into the fiber forming blast.

A further object of this invention is to deposit heat softened or moltenmaterial on a rotor having provision adjacent the periphery forproducing a multiplicity of generally radially outwardly extendingprimary filaments and also having means for mixing the material toincrease its homogeneity prior to forming the primary filaments. Thisfeature renders it possible to eliminate the pulling mechanism or feedrolls and associated guides previously referred to, and also enables theuse of a single ring-type burner for producing the attenuating gaseousblast. Moreover, refining the material as stated above assistsmaterially in reducing to a minimum the formation of slugs or beadsduring the fiber forming phase and improves the quality of the finishedproduct.

A still further object of this invention is to provide an arrangement ofthe above type wherein the temperature of the primary filaments iseither at or closely approaches the attenuating temperature of thematerial before being introduced into the attenuating blast. Thus themajor duty of the gaseous blast is to attenuate the material forming theprimary filaments with the result that a narrower blast may be providedmoving at greater velocities.

It is still another object of this invention to provide a processwherein the glass or similar material is first converted into primaryfilaments and then into fine fibers in a small space or zone by closelyassociated steps. This enables employing lower temperatures at thecentrifugal rotor, and assists in obtaining the desired results withrelatively low rotor speeds. In fact the temperature at the rotor isreduced to such an extent as to enable forming the rotor and associatedparts of relatively inexpensive base metals instead of precious metalssuch for example as platinum.

It is still a further object to convert glass batch to molten glass andthen to fine fibers at a single station and in a closely associatedsequence of steps.

The foregoing, as well as other objects, will be made more apparent asthis description proceeds, especially when considered in connection withthe accompanying drawings, wherein:

Figure 1 is a vertical sectional view through one type of apparatusforming the subject matter of this invention and capable of carrying outthe steps of the improved process;

Figure 2 is a cross-sectional view taken on the line 2-2 of Figure 1;

Figure 3 is a cross-sectional view taken on the line 3-3 of Figure 1;

Figure 4 is a plan view of the rotor;

Figure 5 is a plan view showing a modified arrangement of the burners;

Figure 6 is a fragmentary sectional view show ing a modified form ofrotor periphery;

Figure 7 is a diagrammatic sectional view showing another type of rotorconstruction;

Figure 8 is a diagrammatic view partly in section of a furthermodification of fiber forming apparatus;

Figure 9 is a diagrammatic elevational view of still another type ofapparatus;

Figure 10 is a fragmentary sectional view of a part of the apparatus;and

Figure 11 is a fragmentary sectional view of a modified form ofconstruction.

In general the present invention provides a process and apparatus forforming fibers of varying sizes from glass or materials havingcharacteristics similar to glass. Such materials are of a nature whichenables softening the same in the presence of heat and are capable ofbeing attenuated or drawn out into fine rods or fibers when in asoftened condition. These properties are present in many types ofthermoplastic materials, and are also found in some synthetic resins.While the invention contemplates the formation of fibers from variousdifierent types of materials, nevertheless, it has been primarilydeveloped in connection with the manufacture of glass fibers andaccordingly this material is stressed in the following description ofthe invention.

Briefiy glass cullet such for example as glass marbles, or in keepingwith one aspect of the invention, glass batch is reduced to a softenedstate ranging from a stiff putty-like consistency to a highly fiuidcondition, depending upon the nature of the product and particular modeof operation desired. In any case the softened material is subjected tothe action of centrifugal force of a magnitude sufilcient to cause thematerial to flow along a predetermined path and to draw out the materialinto a relatively thin sheet or into primary filaments or streams,depending upon the nature of the final product required. In themanufacture of fine fibers for use in certain types of insulating mats,it is preferred to separate the softened material into individualelongated bodies or streams as the material flows along its path oftravel under the influence of the centrifugal force. These elongatedbodies or streams are drawn out into what may be termed primaryfilaments by the action of the centrifugal force.

The drawn out material, whether in the form of a relatively thin sheetor in the form of filaments or streams, is projected by the action ofthe centrifugal force into a blast of gas, which moves in a directionextending transversely to the direction of the path of fiow of thesoftened material under the influence of the centrifugal force. As willbe more fully hereinafter described, the blast of gas not only has atemperature which exceeds the softening temperature of the material, butin addition, moves at a velocity sufficiently high to attenuate or drawout the softened material into fibers of the required size. The fibersize may vary over a wide range and depends on the size of the primaryfilament, temperature or viscosity of the material making up the primaryfilament, rate of feed of the primary filament by the centrifugal forceand the velocity as well as the temperature of the blast of gas employedto attenuate the primary filament.

It follows from the foregoing that the softened material may beconsidered as being reduced to fine fibers in two stages of operation.One stage may be considered as the initial drawing out of the softenedmaterial by centrifugal force, and the second stage is the finalattenuation of the previously drawn out material into fibers by the heatand force of the gaseous blast. These two steps in the process areperformed in immediate succession, so that the initially drawn outmaterial is actually introduced into the blast of gas before it has anopportunity to cool appreciably. As a result the blast of gas need notbe relied upon entirely to heat the material to the attenuatingtemperature, and accordingly, the velocity of the blast may be increasedto attenuate the softened material into fibers. Also the thickness ofthe blast may be reduced without the danger of projecting the filamentsor material through the blast. The above feature provides forsubstantially increasing the production of fibers with a thinner blastof ge s, and will be more fully understood as this w sdom proceeds.

Also according to the present inyentien the softened material is refinedas it flows along its path of travel under the influenced! thecentrifugal force. In this connection it will be noted that any cordsthat may be present in the material are actually drawn out in thedirection of flow of the material by the centrifugal force. In oneembodiment of the invention to be presently described in detail thesoftened material is actually separated into individual streams andrecombined prior to being subject to the final drawing out operation bythe centrifugal force. As a result the material is mixed. and any cordsthat may be present are reduced in -iength, so

reference will first be made to the embodiment of the invention shown inFigures 1, 2, 3 and 4. The numeral I9 designates a vertical drive shaftsuitably connected at the upper end to power mechanism (not shown) butadapted to rotate the shaft I9 at the desired speed. The lowerendportion of the shaft I is journalled in a bearing I I, and thisbearing is secured within a collar I2 by a ring. I3 threaded in thelower end of the collar. The. upper end or the shaft 19 is Journalledina bearing I4, and the latter is secured in a collar I5 by a ring I3which is threaded in the upper end of the collar.

The two collars are connected. by concentrically arranged tubes I1 andI8. The inner tube II surrounds the shaft II] in close proximity to thelatter, and the outer tube I8 cooperates with the inner tube to form anannular jacket I9 for a cooling medium such for example as water. It maybe pointed out at this time that thering I3 has an annular jacket 29surrounding ,the portion of the shaft I 0 immediately below the bearingII and connected to the annular Jacket I9 to enable the circulation ofcooling medium through the jacket 29. The desired coolant, such forexample, as water is supplied to. the Jacket I9 by an inlet conduit 2Iwhich enters the jacket I9 through an opening formed atv the upper endof the tube I8 and extends downwardly within the jacket I3 to a positionadjacent the lower collar I2. Thus the coolant is discharged into thejacket I9 adjacent the lower end thereof. The outlet for the coolantwithin the jacket I9 comprises an opening 22 formed in the tube [8adjacent the upper end of the latter. The arrangement is such that thecoolant actively circulates through the jacket I9 and jacket 20 in heatconducting relationship to the vertical shaft Ill. The purpose of suchan arrangement is tomaintain the shaft 40 well below criticaltemperatures during heating of the glass which willv be presentlydescribed. Due to this cooling arrangement, the shaft I9 and associatedparts previously described may be produced from ordinary steels insteadof high temperature resistant materials, and this is of coursedesirable, because it greatly reduces the cost of the construction.

Surrounding the outer tube I8 in concentric relation to the latter is athird tube 23 having a diameter greater than the diameter of the tube I8to form with the latter an annular air passage 24. The opposite ends ofthe tube 23 are respectively connected to the tube I8 by rings 25, andthe latter are formed with openings 26 therethrough. It will also benoted from Figure 1 of the drawings that the upper end of the tube 23has an air inlet opening 21, and this opening is connected to a bloweror a source of air under pressure not shown herein. The air underpressure flows downwardly in the passage 24 through the openings 26, andthe purpose of the air under pressure will become apparent as thisdescription proceeds.

Keyed or otherwise secured to the shaft I9 immediately below the ring I3is a rotor 23 comprising a top section 29, and a bottom section 39. Thebottom section 30 forms a support for the top sections, and is keyed atthe periphery totheadjacent portion of the top section by pins- 3|; Eachpin 3| Is'accommndated ii'rzregisterinfl recesses formed in the adjacentsurfaces oi the a two rotor sections, and. these recesses are of a sizeto permit limited radial movement of one section relative to the other.As will be apparent from the following description, the top section 29is exposed to greater heat than the bottom section, and it is possiblethat this (inferential intemperature may cause the top rotor section toexpand slightly relative to the lower rotor sec-- tion. Such a conditionis compensated for with out causing undue warpage of the parts by thekey'connection 3|. In order to minimize the transfer of heat from thetop rotor section 29 to the bottom rotor section 30, a suitablehightemperature insulation such for example as glass wool 32, is interposedbetween the two sections.

As shown in Figure I of the drawings, the-top surface of the bottomrotor section 39 is formed with an annular recess 33 which is closed bythe bottom surface of the top rotor section and ac commodates the hightemperature insulationfli.

Positioned directly below the rotor 28 is a fan 34 having a hub 35 keyedon the shaft I9 and secured in place by a nut 36 which is threaded onthe lower end of the shaft Ill. The fan 34 is substantially cup-shapedin cross section having an upwardly extending radially outwardly flaredflange 31 at the periphery thereof. The flange 31 encircles the lowersection of the rotor 28, and is spaced a slight distance outwardly fromthe periphery of the rotor to form with the periphery of the rotor arestricted upwardly directed annular discharge passage 38 for the air.

Projecting radially outwardly from the hub 35 of the fan to theperipheral flange 31 is a series of vanes 39 arranged to move airradially outwardly from the hub 35 through the restricted dischargepassage 38. Referring again to Figure 1 of the drawings, it will benoted that the rotor 28 is formed with a series of openings 40' spacedfrom each other around the axis or the shaft In and registering with theopenings 26 at the lower end of the annular air passage 24. The openings40 extend entirely through both sections of the rotor 28 so that the airunder pressure issuing from the openings 26 enters the fan 34 adjacentthe hub 35. As stated above this air is conveyed to the annulardischarge opening 38 by the vanes 39, and is discharged at substantialvelocity in an upward direction from the opening 38. The air serves tocool the parts of the equipment during its flow from the inlet opening21 to the annular outlet passage 38, and also has an additionalimportant function which will be more fully hereinafter described.

The air flowing from the annular passage 24 to the fan 34 is preventedfrom escaping laterally outwardly over the top surface of the rotor 29by a tubular shield 4| having the lower end secured to the top section29 of the rotor 29 in concentric relation to the axis of the shaft III.The upper end of the shield 4| surrounds the lower end of the tube 23 inclose proximity thereto, and a suitable seal may be provided for sealingthe space between the upper end oi. the tube 4| and the adjacent surfaceof the tube 23. The seal 42 comprises a pair of axially spaced rings 43and 44. The ring 44 is welded or otherwise permanently secured to theouter tube 23 and the ring 42 is positioned to have a bearing engagementwith the top edge of the tubular. shield M. The ring 43 also has asliding fit with. the outer surface of the tube 23 and isaurgedi.

aeoasea into frictional contact with the upper end of the tube 4| bycoil springs 45. The coil springs 45 are spaced equal distances aroundthe tube 23 and are located between the rings 43 and 44. The springs arerespectively held in position by suitable pins 46 which extend throughregistering openings formed in the rings 43 and 44. With the abovearrangement the shield 4| cooperates with the outer tube 23 to form asealed passage for the air from the fan 34 to the passage 24.

Referring now more particularly to Figure 2 of the drawings, it will benoted that an annular support 41 is positioned directly above the rotor28. The support 41 has an inner tube 48 which encircles the air shield4| in concentric relation to the axis of the shaft l0, and also embodiesa tube 48 positioned in concentric relation to the tube 48. The tube 49has a diameter substantially greater than the tube 48 to form with thelatter an annular space 50 having the lower end closed by an annularplate The upper end of the annular space 50 is closed by a similarannular plate 52, and the two plates are formed with circumferentiallyspaced aligned openings 53. The aligned openings 53 are respectivelyconnected by a tube 54, and these tubes form vertical chambers 55.

Surrounding the lower end portion of the tube 49 and concentricallyarranged with respect to the latter is a pair of tubes 56 and 51. Thediameter of the tube 56 is substantially greater than the diameter ofthe tube 49, and cooperates with the latter to form an annular casing58. The tube 57, on the other hand, is of greater diameter than the tube56, and provides an annular jacket 59 for coolant. The cooling medium isintroduced into the jacket 59 adjacent the lower end thereof through asupply conduit 60, and is discharged from the jacket through the conduit6| adjacent the upper end of the jacket. Thus the cooling medium flowsin heat conducting relation to the casing 58 and prevents excessive heattransfer from the annular casing to the outer wall or tube 51 of thesupport.

Upon reference to Figure 1 of the drawings it For the purpose ofillustration the source of supply of molten glass comprises an orthodoxforehearth diagrammatically indicated by the numeral E2 and having anoutlet 53 communicating with the upper end of only one of the tubesdesignated by the numeral 54'. The molten glass flows by gravitydownwardly through this tube and is deposited on the top surface of therotor 28. The remaining tubes serve as housings for gas combustionburners 64 of the radiant type. One burner 64 is suitably supported ineach tube 54 at the bottom of the latter in such a position that theflame is direct-ed against the rotor and the desired combustible mixtureof gases is supplied to the burners by conduits 65 extending upwardlythrough the respective tubes 54 to a source of supply. The purpose ofthese burners is to maintain or heat the glass deposited on the rotor 28to the proper temperature.

The top surface of the rotor 28 registering with the lower ends of thevertical tubes 54 is formed with an annular recess 66, and the moltenglass discharged from the tube 54 collects in this re- 0855. Theradially outer Wall of the recess 68 is formed by an annular rib Blprojecting upwardly from the top surface of the rotor and cooperatingwith an upstanding annular flange 68 at the periphery of the rotor toform a second annular recess 69. The annular recess 68 is spacedradially outwardly from the annular recess 66 in a position Where itdoes not receive glass directly from the tube 54 and the flange 68extends upwardly beyond the elevation of the rib 51. The top edge of therib 61 and the corresponding surface of the flange 68 are serrated toprovide a multiplicity of closely spaced radially extending grooves HIand H. Although the spacing between adjacent grooves may varyconsiderably, nevertheless, it is preferred to provide as many groovesas possible without disrupting the operation. In practice the centerdistances between adjacent grooves may be as small as one-sixteenth ofan inch.

Operation of rotor assembly The glass deposited in the annular recess 66in the rotor 28 is more or less uniformly distributed throughout therecess as the rotor revolves about the axis of the shaft I0 and isheated by the radiant burners 64. The temperature to which the glass isheated may vary considerably depending upon the nature of the finalfibers required, but in any case, this temperature exceeds the softeningpoint of the glass. The molten or heat softened glass contained withinthe recess 66 in the rotor 28 is subjected to the action of centrifugalforce resulting from rotation of the rotor, and flows radially outwardlyalong the rotor under the influence of this force. Any cords that may bepresent in the body of glass tend to orient themselves in the generaldirection of glass flow and are drawn out to some extent.

The heat softened body of glass is divided into a multiplicity of smallstreams as it flows across the serrated rib 81 on the rotor 28 and theserrations formed by the grooves 10 tend to cut the cords into shorterlengths. After the body of glass passes over the annular serrated rib 61the individual streams are combined in the annular recess 69 in therotor and the resulting body of glass passes outwardly over the serratededge of the annular flange 68 at the periphery of the rotor 28. Itfollows from the above that the body of heat softened glass is refinedand rather vigorously mixed as it flows radially outwardly over therotor 28 under the influence of the centrifugal force. The arrangementis such as to substantially improve the homogeneity of the glass andeliminate cords of a size which would have any appreciable detrimentaleffect on the product or on the final fiber forming steps of theprocess.

As the heat softened glass passes over the annular serrated edge of theperipheral flange 68, it is again separated into a multiplicity ofindividual streams which are drawn out by the action of centrifugalforce to provide primary filaments or streams indicated in Figure 1 ofthe drawings by the numeral 12. The diameter of the primaries I2, or inother words, the extent to which the streams are drawn out bycentrifugal force depends largely upon the peripheral speed of the rotorand the viscosity of the heat softened body of glass flowing outwardlyalong the rotor. As will be presently described the primaries I2 areprojected by the action of centrifugal force into an intensely hot highvelocity blast B and are further drawn out or attenuated into finefibers by the heat and force of the blast B. Primaries of a diameterrendering it possible to produce extremely fine fibers of two microns orless inrdi-ameter may be obtained by rotating a twelve-inch diameterrotor 28 at a speed in the neighborhood of between 500 and 1000 R. P. M.and with glass heated. to temperatures as low as 1500 or 11600 F. Suchspeeds and temperatures are well within arange which renders itpractical to form the rotor and associated parts of inexpensive basemetals such as nickel, chrome or. tungsten alloy steels.

It is also important to note that the formation of primary filaments orstreams I2 is effected continuously as long as glass is supplied to therotor 28 and accidental interruptions in the primary forming phase arepractically entirely eliminated. Moreover, initial starting of theprimary forming phase following an interruption from any cause isautomatic in that manual handling of the primaries is not'required. Thisfeatore-not only greatly facilitatesstarting and reduces down time" ofthe apparatus, but in addition' makes it unnecessary to employ skilledattendants. Furthermore, since the apparatus does not require manualmanipulation of the primaries to effect starting of the formingoperation the primaries may be positioned in much closer relationship,and accordingly a greater number of primaries may be introduced into ablast B of given width. This contributes materially to increasing thefiber forming production without increasing the size of the equipment.

It has been stated above that the primaries 12 are projected radiallyoutwardly by centrifugal force into a blast B of gas. The blastsurrounds the periphery of the rotor 28 in substantial concentricrelation to the axis of the rotor and the location of the source of theblast is so determined that the blast passes the peripheral flange 68 onthe rotor in such close relationship thereto that the primaries T2 arefed into the blast before they have an opportunity to cool appreciably.Thus the temperature of the primaries entering the blast B mayapproximate the attenuating temperature of the glass so that the blastneed not be relied upon to actually heat the primaries to theattenuating temperature. For reasons which will become more apparent asthis description proceeds, the above feature simplifies obtaining ablast having the velocity required to attenuate the heat softenedprimaries 2 to fine fibers.

Inthe present instance the blast B flows in a downward direction and thefibers formed from theprimaries are blown in a corresponding direction.These fibers may be collected in the form of a mat, if desired, on aconveyor (not shown) supported below the apparatus. As the ring-likeblast B flows downwardly around the periphery of the rotor 23, there isa tendency for the blast to neck-in" around the rotor, and this isavoided by the air under pressure discharged from the restricted annularpassage 38. Upon reference to Figure 1 of the drawings, it will be notedthat the air issuing from the annular passage-3 8 flows upwardly andoutwardly along the peripheral flange 58. Thus the air has theadditional function of acting in effect a a support .to hold theprimaries 72 leaving the rotor 28 in a. plane substantially normal tothe blast B. In other words, the air under pressure in conjunction withthe centrifugal force acting in a radially outward direction on theprimaries l2 insures feeding the primaries endwise into the blast, eventhough primaries are in a relatively soft condition.

In accordance with this invention the blast B is composed substantiallyentirely of products of combustion obtained by burnin a combustiblemixture of gases within a chamber 13 and discharging the burned gasesfrom the chamber through a restricted outlet opening in one wall of thechamber. The chamber I3 shown in Figure 1 of the drawings is annular inconfiguration and is formed in an annular refractory block 14 uitablysupported in the annular casing 58. The upper end of the chamber 13 isclosed by an annular ring 15 having a series of passages 16 therethroughfor a combustible mixture of gases. These gases are conducted to thepassages 16 by an annular manifold 11 suitably secured to the support 41by fastener elements 18 and communlcatlng with a gas mixing device (notshown) through conduits 19.

The bottom wall of the chamber 13 is formed with an annular outletopening concentrically arranged with respect to the axis of rotation 01'the rotor 28 and having a diameter such that the gases issuing therefromflow downwardly in the form of a ring past the periphery of the rotor.It is also pointed out at this time that the plane occupied by thedelivery end of the outlet opening 80 lies in such close relationship tothe plane including the top edge of the annular peripheral flange 68 onthe rotor 28 that the primaries 12 enter the blast before the latter hasan opportunity to expand appreciably. In other words the primaries areprojected into the portion of the blast which is at substantially themaximum available temperature and which is traveling at practically themaximum velocity. Thus full advantage is taken of the heat and velocitycharacteristics of the blast B in reducing the primaries to fine fibers.

Operation 0! burner The combustible mixture of gases enters the annularcombustion chamber 13 through the passages 16 in the top wall or ring15, and are ignited. As the gas mixture burns within the chamber 13 thewalls of the latter become extremely hot and the rate at which theincoming gas mixture burns is substantially increased. The resultinghigh rate of combustion causes a great expansion of the burnedgaseswithin the chamber 13, and since the outlet opening is substantiallyrestricted, it follows that these gases are discharged fromthe chamberin the formof an intensely hot high velocity blast.

The type of combustible gas used may be of any suitable kind, but forreasons of economy, it is preferably an ordinary fuel gas, such asnatural or manufactured fuel gas. This gas is mixed with the properamount of air by means of the orthodox air and fuel mixers. The gas andair mixture is taken from the mixer at moderate pressures ofapproximately one to five pounds per square inch, but may beconsiderably higher if desired. The aim is to feed as much of themixture as possible into the chamber 13 without causing the combustionto become unstable or to take. place at the outside of the chamber, orto cease altogether. This mixture is fed into the chamber 13 atvelocities below the rate of flame propagation of the particular mixturein the atmosphere. However, after the refractory walls of the chamberbecome heated, it is possible to increase the rate of feed of themixture into the chamber l'z'above the rate of flame propagation.

Thecross sectional area of the annular outlet opening 80 is soproportioned with respect to the size of the chamber 13 or with respectto the quantities of gas burned that the products of combustion aredischarged from the opening 80 in the form of a blast having atemperature in excess of the softening temperature of the glass andhaving a velocity sufficiently high to draw out or attenuate thesoftened glass into fibers of the required size. The combustible mixtureof gases may be burned in such quantities with respect to the volume ofthe chamber 13 as to produce a rate of combustion of the gases withinthe chamber I3 sufliciently high to force the burned gases from thechamber in the form of a blast having a temperature as high or higherthan 3000 F. and a velocity as high or higher than 1200 feet per second.

It will, of course, be understood that the cross sectional area of theoutlet opening 80 may be varied with respect to the size of thecombustion chamber 13 to obtain blasts having different temperature andvelocity characteristics. Outlet openings of greater cross sectionalarea permit burning a greater amount of gas and result in generatinggreat heat in the blast. However, as the size of the outlet opening 80is increased the velocity of the blast issuing from the outlet openingis decreased, and therefore, it is preferred to form the outlet openingwith a cross sectional area no greater than necessary to obtain in theblast the heat required to maintain the glass at the desired attenuatingtemperature. As stated above, the blast need not be relied upon toactually heat the glass, and as a consequence, the size of the outletopening 80 may be reduced to a somewhat greater extent than would bepractical where the primaries are actually melted or softened by thetemperature of the blast.

Reference has also been made above to the fact that the primaries 12 areinitially drawn out by the action of centrifugal force resulting fromrotation of the rotor, and are immediately thereafter attenuated intofine fibers by the force of the blast B. The magnitude of thecentrifugal force depends upon the peripheral speed of the rotor 28, andis sufficient to perform the additional function of projecting theprimaries end wise into the blast B in close proximity to the outletopening 80 where the temperature and speed of the blast is at a maximum.The centrifugal force, however, is substantially less than the force ofthe gas in the blast B, so that this force actually turns the ends ofthe primaries I2 downwardly in the blast B and attenuates the primariesinto fine fibers.

The size of the fibers depends on the size of the primaries l2,temperature of the primaries, rate of feed of the primaries, velocityand temperature of the blast B. Either or all of these may be variedwithin limits to obtain fibers of one micron or less in diameter to twoand one-half microns or more in diameter.

The embodiment of the invention shown in Figure 5 of the drawingsdiffers from the above construction in that the ring-like blast Binstead of being produced by an annular burner is obtained by amultiplicity of separate burners Bl arranged in rows concentric with theaxis of the rotor 28. The burners 8| in each row are spaced apart, butare staggered wtih respect to the burners in adjacent rows, so that theblast issuing from one burner effectively bridges the gap betweenadjacent burners in the next row. The individual burners 8| operate onthe same 12 principle as the burner shown in Figure 1 and need not bedescribed in detail.

In the first described form of the invention the body of glass or heatsoftened material is separated into individual streams or primaries 12by a multiplicity of grooves 1| formed by serrating the top edge or theperipheral flange 68. If desired, the primaries 12 may also besuccessfully produced in the manner shown in Figure 6 of the drawings byextending the peripheral rotor flange 82 upwardly and forming amultiplicity of small holes 83 in the flange. The holes 83 are spaced inclose proximity to each other circumferentially of the flange 82, andcoact with the centrifugal force to produce well defined primaryfilaments or streams.

Figure 7 of the drawings is a diagrammatic illustration of apparatusrendering it possible to actually melt the body of glass in the rotorand thereafter to discharge the glass in the form of a multiplicity ofseparate primaries by the action of centrifugal force. The rotor isdesignated by the numeral 85 and is supported for rotation on a verticalshaft ID in much the same manner as described in connection with thefirst embodiment of this invention. However, in the present instance therotor 85 is formed of a high heat resistant material, such for example,as platinum, molybdenum, tantalum, ceramic materials or any combinationof these and other materials.

The rotor 85 is shaped to provide an annular receptacle 81 into whichglass batch in the form of fine powdered material or in the form ofbriquettes of intermixed glass ingredients may be fed. Alternatively,glass cullet such as granu lated glass or glass marbles may also be feddirectly into the annular receptacle 81. Any suitable means may beemployed to feed the selected material into the receptacle, such forexample, as a hopper and a chute leading from the hopper to a positiondirectly above the receptacle.

In the present instance the glass in one form or another is heated byradiant burners 9U supported above the rotor 85 on a suitable fixedsupport in a position to direct the flames against the material or glassin the receptacle 81. However, it will be understood that the receptacle8! may be heated in other ways such, for instance, through means ofelectric current. This current may be passed through the walls of thereceptacle by making the rotor the secondary of a transformer having itsprimary in the form of a coil (not shown) connected to a source ofalternating current. With such an arrangement current is induced in thewalls of the receptacle 8! and heats the contents of the latter to themelting temperature.

Regardless of the specific form oi. heating selected, the contents ofthe receptacle are melted or softened to such an extent that they flowgenerally radially outwardly under the influence of the centrifugalforce obtained as a result of rotating the receptacle about the axis ofthe shaft ill. The peripheral edge of the receptacle at the top of thelatter may be formed with a multiplicity of closely spaced openingssimilar to the openings 83 of Figure 6, and the heat softened materialfiows through the openings under the influence of centrifugal force toform individual primaries. These primaries are projected into a blast ofgas, and are attenuated into fibers by the heat and force of the blastin the same manner noted in connection with the modification shown inFigures 1 to 4 inclusive.

ecal-ice .fln practicingzthevprocess with :the: apparatus tfeaturesiniiiguresfi and 7, itis posslbleto heat iglass batch-material in thereceptacle .81 Just enough to fuse Or soften the material'sothat it'will compact against the outer wall of the receptacle and pass throughthe openingstll in the form of batch rods. The rods are then projectedinto a blast of gas similar to the blast B and hav- 'ingsuflicienttemperature to melt the batch rod "to 'form glass which is attenuated bythe force of the blast into fibers.

In Figure 8 of .the drawings.anotherapparatus :for producing fine glassfibers is shown. In dettail, the numeral I indicates a disk supportedfortrotation about a vertical axis and having a serrated peripheral edgeI 0 I 'simulatingsawi teeth. Theishaft N2 onwhichthe diskis secured isjournalled in suitable hearings 'and' is connected to aprime moverrsuchfor example as an electric ;motor M3. "the disk [00 is a receptacle I04containing a sup- .ply of molten glass and having adischarge opening in:the ibottom wall through which molten glass flows as a stream under theinfluence of .:gravity. The opening is so'located with respect to thedisk Hi0 thatthe molten glass is deposited on the disk adjacent theserrated peripheral edge of the latter. Since the disk Hill is rotatingabout the axis of the shaft I02, the molten glass is directed radiallyoutwardly under the influence of centrifugal force, and is separatedbythe teeth at the periphery of'the disk into individual streams.

Supported directly below the disk we is a block of refractory materialhaving a recess [06 in the top surface and having an intake Hi1 throughwhich a combustible mixture of gases is introduced into the-recess.These gases are ignited in the recess 1B5 'and'the products ofcombustion serve toheat. the disk which forms the top wallof the recessN16. The disk lllil'is spaced above the top of the block I8 5 to form arestricted annular outlet opening lill between thetop of the block andthe underside of the peripheral edge of the disk. The products ofcombustion which takes place in the recess Hi8 escape through theannular restricted outlet opening l ll'l and'for'm a ring-like blast'ofintensely hot gas moving at substantial velocity. The primaries orstreams discharged from the periphery of the disk lllll under theinfluence of centrifugal forceare projected into this blastrandarefurther-attenuated into fine fibers.

Figure 9'of the drawings features an arrange ment somewhat similar tothe above, except that thedisk Kid is heated from above by one or moreradiant types of gascombustion burners H9. The moltenglass primariesflowing radially-outwardly from the periphery of the disk Hill under theinfluence of the centrifugal force are interrupted by an annular shieldl l I and are directed by this shield in a downward direction toward aconveyor 0r belt H2. The fibers are conveyed toward the belt by theaction of suction produced by drawing air through a casing H3 suitablysupported below the conveyor.

In Figure 11 of the drawings a construction is shown which may beidentical to the embodiment shown 'in Figure 1, except that a ring I I5is positioned between the rotor 28 and the ring-like blast B. The ringH5 is attached to the rotor 28 at points spaced circumferentially of therotor by spokes I W and the outer edge TI 1 extends to a positionimmediately adjacent the blast B. it will also be noted from Figure 1 1that the outer an- .nularedgel ll. of thering is. locatedina positionSuitably supported directly above Gil atofinterceptthastreamsnf glass:issulngrfromthe peripheral' edge H ofthesrotor .28, and since the ring II5 rotates as a. unit with the .rotor, the

streams are ied intothe blast B by centrifugal force avoided, and inaddition, the outer annular edge ll! of the ring assists the stream ofair supplied by the blower 34 to prevent the blast from cur ing inwardlytoward the rotor.

We claim:

1. The process of making glass fibers which comprises flowing a body ofheat softened glass in a generally radially outward direction by theaction of centrifugal force, mixing the glass 'as it flows outwardlyunder the influence of the centrifugal force to increase the homogeneityof the glass by separating the softened body of glass into streams,recombining the streams of glass upon continued flow of the glass bodyunder the action of said centrifugal force to aid in mixing the glass,again separating the glass into a multiplicity of individual glassstreams as the glass continues to flow under the influence of thecentrifugal force, projecting the last-named streams into a blast of hotgas moving at substantial velocity in a direction extending transverselyto the direction of how of the glass, and attenuating the streams ofglass into fibers by the heat and force of the blast.

2. The process of making glass fibers which comprises burning acombustible mixture of gases and discharging the burned gases in theform of a'single ring-like blast of gas moving downwardly at a ratesufficient to attenuate softened glass into fine fibers, flowing a bodyof heat softened glass by centrifugal force in a generally radialdirection normal to the movement of the blast. separating the body ofglass as it flows under the influence of centrifugal force into amultiplicity of individual streams of glass, projecting the streams withsufficient force to enter but not go through the ring-like blast, andreheating and drawing out the streams into fine fibers by the heat andforce of the blast.

3. The process of making glass fibers which comprises burning acombustible mixture within an annular chamber and discharging theprodnets of combustion from the chamber in the form of an annular blastmoving in one direction at a velocity sufficient to draw out heatsoftened glass into fibers, flowing a body of heat'softened glass indirections extending generally radially 'outwardly from the axis of theannular blast by the action of centrifugal force, mixing the glass as itflows outwardly under the influence of centrifugal force to increase thehomogeneity of the glass by separating the softened body of glass intoindividual streams and by stretching out any cords in the glass in adirection extending transversely to the direction of flow of the blast,recombining the glass streams during continued outward flow of the glassand again separating the recombined glass into individual streams,projeoting the inidividual streams of glass endwise into the annularblast by the action of the centrifugal force and drawing out the'streamsto form fibers by the heat andforce of the blast.

4. The process of making glass fibers which comprises flowing a body ofheat softened glass along a predetermined path by the action ofcentrifugal force, successively separating the body of glass intoindividual streams and recombining the streams of glass while the bodyof glass moves along said path of travel under the influence ofcentrifugal force and finally forming the glass into streams, projectingthe streams of glass endwise into a blast of extremely hot gas moving ata high velocity in a direction extending transversely to the path ofmovement of the glass body, and further attenuating the streams of glassinto fine fibers by the heat and force of the blast.

5. The process of making glass fibers which comprises burning acombustible mixture of gases and discharging the products of combustionin the form of a ring-like blast of gas moving at a rate sufficient toattenuate softened glass into fine fibers, flowing a body of heatsoftened glass in a generally radially outward direction from theapproximate center of the blast by the action of centrifugal force,separating the body of glass into a multiplicity of individual streamsof glass and recombining them while said body flows under the influenceof the centrifugal force and then forming the glass into individualstreams projecting the streams of glass endwise into the annular blastby the action of centrifugal force, and attenuating the drawn outstreams into very fine fibers by the heat and force of the blast.

6. Apparatus for producing glass fibers comprising means for producing aring-like blast of gas having a temperature exceeding the softeningtemperature of glass and having a velocity sufficiently high toattenuate softened glass into fibers, a rotor supported within theconfines of the ring-like blast and having concentric recesses thereinfor supporting a body of heat softened glass. and means for rotating therotor at a speed determined to provide the centrifugal force required toflow the heat softened glass successively through said recesses and toproject the glass beyond the periphery of the rotor into the blast.

'7. Apparatus for producing glass fibers comprising a rotor having anannular recess in the top surface adapted to retain a body of heatsoftened glass and having a second annular recess in said surfaceconcentrically arranged with respect to the first recess, an annularupstanding rib separating the recesses, an annular upstanding flange atthe periphery of the rotor forming the outer wall of the outermostrecess, means for rotating the rotor at a speed determined to providethe centrifugal force required to flow the heat softened glass from theinner annular recess generally radially outwardly over the top surfaceof the annular rib into the outer annular recess and over the topsurface of the upstanding peripheral flange into the space beyond theperiphery of the rotor, and means for attenuating the heat softenedglass entering the space beyond the rotor including a blast of gashaving a temperature exceeding the softening temperature of the glassand having a velocity sufficiently high to draw out the softened glassinto fibers.

8. Apparatus for making glass fibers comprising means for producing aring-like blast of gas having a temperature exceeding the softeningtemperature of glass and having a velocity sufiiciently high toattenuate heat softened glass into fibers, a rotor supported within theconfines of the ring-like blast with the plane of rotation thereofsubstantially normal to the direction of movement of the blast, saidrotor having an inner annular recess adapted to contain a body of heatsoftened glass and having an outer annular recess, an annular ribseparating the recesses and having a multiplicity of circumferentiallyspaced grooves in the top surface thereof, an annular upstanding flangeat the periphery of the rotor forming the outer wall of the outermostannular recess and also having a multiplicity of circumferentiallyspaced grooves in the top surface thereof, means for rotating the rotorat a speed determined to provide the centrifugal force required to flowthe heat softened glass from the inner annular recess radially outwardlyover the grooved top surface of the rib into the outer annular recessand over the grooved top surface of the peripheral flange into saidblast.

9. Apparatus for producing glass fibers comprising a rotor supported forrotation, means for depositing a body of heat softened glass on the topsurface of the rotor, means for rotating the rotor at the speeddetermined to provide the centrifugal force required to fiow the glassgenerally radially outwardly from the peripheral edge of the rotor, aring surrounding the periphery of the rotor in radial spaced relationthereto and positioned to intercept the glass flowing outwardly from theperiphery of the rotor, and means for rotating the ring as a unit withthe rotor.

10. Apparatus for producing glass fibers comprising a. rotor havingprovision for supporting a body of heat softened glass on the topsurface thereof, means for producing a blast of gas having a temperaturewhich exceeds the softening temperature of glass and having a velocityhigh enough to attenuate the heat softened glass into fibers, means forflowing the blast past the periphery of the rotor in a directionextending in the general direction of the rotor axis, means for rotatingthe rotor at a speed determined to provide the centrifugal forcerequired to flow the heat softened glass generally radially outwardlyalong the top surface of the rotor and to project the glass beyond theperiphery of the rotor toward the blast, and a ring surrounding theperiphery of the rotor in radial spaced relation thereto and rotatableas a unit with the rotor, said ring being located to intercept the glassflowing from the periphery of the rotor and to direct the glass leavingthe outer edge thereof into said blast.

11. The process of making glass fibers which includes burning acombustible mixture of gases and discharging the burned gases in theform of a ring-like blast of gas moving at a rate sufficient toattenuate glass into fine fibers, moving a mass of heated glass bycentrifugal force in a generally radial direction transverse to themovement of the blast, separating the mass of glass as it fiows underthe influence of centrifugal force into a multiplicity of individualelongated bodies of glass, projecting the elongated bodies of glass withsuflicient force to enter but not go through the ring-like blast, andreheating and drawing out the elongated bodies into fine fibers by theheat and force of the blast.

12. The process of making glass fibers which includes burning acombustible mixture of gases and discharging the burned gases in theform of a ring-like blast of gas moving at high velocity, moving a bodyof heated glass by centrifugal force in a generally radial directiontransverse to the movement of the blast, separating the body of glass asit moves under the influence of centrifugal force to form a multiplicityof rods of glass, projecting the rods with sufiicient force 17 to enterbut not go through the ring-like blast,

18 UNITED STATES PATENTS and reheating and drawing out the rods intofine Number Name Date fibers by the heat and force of the blast. 2192944Thomas Man 12, 1940 GAMES SLAYTER. 2,328,714 Drill et a1 Sept. '7, 1943CHARLES J, STALEGO 5 2,338,473 Von Pazsiczky Jan. 4, 1944 2,450,363Slayter et a1 Sept. 28, 1948 REFERENCES CITED FOREIGN PATENTS Thefollowing references are of record in the Number Countr 3! Date file ofthis patent- 10 215,101 Switzerland June 15, 1941 Germany Mar. 6, 1933UNITED STATES PATENT OFFICE Certificate Patent No. 2,609,566 7 PatentedSeptember 9, 1952 Games Slayter and Charles J. Stalego Applicationhaving been made jointly by Games Slayter and Charles J. Stalego, theinventors named in the patent above identified, and Owens-00minFiberglas Corporation, Toledo, Ohio, a corporation of Delaware, theassignee, for t e issuance of a certificate under the revisions of Title35, Section 256 of the United States Code, de leting the name of e saidGames Skater from the patent as a 'oint inventor, and a showing andproof of facts satisfying e requirements of the sai section havin beensubmitted, it is this 27th day of March 1962, certified that the name ofthe said ames l$13. tellis hereby deleted irom the said patent as ajoint inventor with the said Charles ta ego.

EDWIN L. REYNOLDS, First Assistant Commissioner of Patents.

Notice of Adverse Decision in Interference In Interference No. 86,795involving Patent No. 2,609,566, C. J. Stalego, Method and apparatus forforming fibers, final judgment adverse to the patentee was rendered Jan. 30, 1958, as to claims 2, 11 and 12.

[Ofiicial Gazette June 12, 1.962.]

